Figure 6
(a) Mid-IR test station to characterize the performance of our Si-on-BTO waveguide sensor. The probe light from a tunable pulsed laser (λ = 2.4 μm to 3.8 μm) was collimated into a mid-IR fiber using a reflective lens (RL) and then butt coupled into the waveguide. Meanwhile, the analytes was dropped onto the waveguide surface through a syringe. The mid-IR light emitted from the waveguide end facet were focused by a barium fluoride biconvex lens and then imaged by an InSb camera. (b) The core of the mid-IR fiber was lined up with the front facet of the Si waveguide. The fine alignment between the optical fiber and the waveguide was monitored by an upper microscope (MO).
